IL-27 is expressed in activated antigen presenting cells including monocytes, endothelial cells, and dendritic cells, for example mouse CD4 splenocytes. This purified antibody has been tested for use in western blotting. Specific conditions for reactivity should be optimized by the end user. Expect a band approximately 23 kDa in size corresponding to the mature mouse EBI3 protein, a non-glycosylated polypeptide chain consisting of 207 amino acids, by western blotting in appropriate cell lysate or extract.